Lijo,

It looks like you are describing two things: the TTL (or hop limit in IPv6
parlance) which decrements by one by each router, and some timestamp which
can be used to measure end -to-end latency. I'm assuming the latter.

I'm also assuming you are doing this as part of an experiment, to look at
the end-to-end/hop-by-hop latency. In that context, you probably aren't
looking for standardizing that (or even standards-compliance during your
experiment), but more at an implementation technique to keep that
information.

Of course, the answer depends entirely on the information we are missing.
But assuming you are playing with the OpenWSN implementation, there is
already an application called rrt which sends the ASN as application
payload at the source, and records the ASN when the DAGroot has received
that. You can then substract one by the other and do some stats. Please ask
further questions to the OpenWSN community [1] as such technical discussion
on a particular implementation doesn't belong on the 6TiSCH WG ML.

If you are using the commercial SmartMesh IP solution by Linear Tech [2],
good news, all of that is already built in. The manager (~DAGroot) keeps
track of timing and can send you average latencies for each of your nodes.
If you're interested, you can look at these numbers "live" on deployments
in Argentina [3,4] or California [5]. As you might imagine,
latency/throughput/lifetime trade-off for one another, so there is a handy
"performance estimator" tool you can use [6,7]. For further question on
this topic, please use www.dustcloud.org.

Finally, looking at lowering latency in 6TiSCH has been an important
research topic in the last year or so. Look for example at the "Low-Latency
Scheduling Function" [8] work which lowers the per-hop latency to 10's of
ms withing the 6TiSCH framework.

Thomas

[1] www.openwsn.org
[2] www.linear.com/dust
[3] http://www.savethepeaches.com/
[4] PEACH: Predicting Frost Events in Peach Orchards Using IoT Technology.
Thomas Watteyne, Ana Laura Diedrichs, Keoma Brun-Laguna, Javier Emilio
Chaar, Diego Dujovne, Juan Carlos Taffernaberry, Gustavo Mercado. EAI
Endorsed Transactions on the Internet of Things, to appear in 2016.
[5] http://www.snowhow.io/
[6] http://www.linear.com/docs/42452
[7] Industrial IEEE802.15.4e Networks: Performance and Trade-offs. Thomas
Watteyne, Joy Weiss, Lance Doherty, Jonathan Simon. IEEE International
Conference on Communications (IEEE ICC), Internet of Things Symposium,
London, UK, 8-12 June 2015.
[8] LLSF: Low Latency Scheduling Function for 6TiSCH Networks. Tengfei
Chang, Thomas Watteyne, Qin Wang, Xavier Vilajosana. IEEE International
Conference on Distributed Computing in Sensor Systems (DCOSS), Washington,
DC, USA, 26-28 May 2016.

On Thu, Aug 25, 2016 at 7:57 AM, Lijo Thomas <[email protected]> wrote:

> Hi all,
>
> We are working on problem which needs the *Time to Live (TTL) information*
> in terms of *ASN * to be included as part of the Packet.
>
> We require the intermediate nodes to update TTL at each hop.
>
> How this information can be passed in a 6tisch framework.
>
> Suggestions are welcome..
>
> Thanks & Regards
> Lijo Thomas
>
>
>
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-- 
_______________________________________

Thomas Watteyne, PhD
Research Scientist & Innovator, Inria
Sr Networking Design Eng, Linear Tech
Founder & co-lead, UC Berkeley OpenWSN
Co-chair, IETF 6TiSCH

www.thomaswatteyne.com
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